A parametric investigation into the flexural properties of singly curved composites reinforced with 3D-integrated woven fabrics

In this study, the effect of curvature on the flexural behavior of 3D integrated woven fabric composites was initially investigated. After optimizing the effect of curvature, two strengthening methods (thickening upper skin and foam-filling) were applied on curved 3D integrated woven fabric composites separately and simultaneously. Normalized-weight flexural properties were used as an efficiency index to analyze and compare the efficiency of both methods. Results showed that as curvature increases from 0 to 0.007 and 0.014 cm ⁻¹ , peak load increases about 29.8 and 36.7%, respectively. In addition, as upper skin thickness increases, most of flexural properties increase and then decrease. Moreover, flexural properties improved by injecting polyurethane foam into the empty core. Furthermore, applying both methods on curved 3D integrated woven fabric composite sample made an outstanding improvement in flexural properties. That is, the flexural peak load, stiffness, and total energy absorption increased 244.4, 142.7, and 496.4%, respectively, in comparison to the unreinforced 3D integrated woven fabric composite sample. Based on the normalized results, it could be concluded that applying thickening upper skin and foam-filling the core methods separately have no considerable improvement in specific flexural properties; however, applying both methods simultaneously improved specific peak load and specific total energy absorption 35.3 and 134.1%, respectively.